Examples of a method of suppressing an excitation inrush current in a transformer include a phase-control input method in which a breaker is input in a specific phase of a three-phase power supply. Conventionally, the following technique is disclosed. That is, as for a first closing phase on which a closing operation is performed first among three phases, a closing phase in which an input magnetic-flux error that is the absolute value of a maximum error between a stationary magnetic flux and a residual magnetic flux at an input point becomes a minimum value is calculated and set as a target closing phase for the first closing phase based on the residual magnetic flux in the first closing phase and the already-obtained pre-arc characteristics and closing-time variation characteristics of the three-phase breaker while assuming an arbitrary reference phase of 0 degree as a reference point. As for the two remaining phases, a closing phase for which an input magnetic-flux error becomes a minimum value when a residual magnetic flux is zero is calculated and set as a target closing phase for the two remaining phases based on the already-obtained pre-arc characteristics and closing-time variation characteristics of the three-phase breaker while assuming the arbitrary reference phase of 0 degree as the reference point. The time obtained by adding up the time from the reference point to the target closing phase for the two remaining phases and the delay time corresponding to the integer multiple of the preset cycle of a three-phase power supply is set as a target closing time of the two remaining phases (for example, Patent Literature 1 mentioned below).